Method of attaching leather soles to shoes



Patented Dec. 17, 1935 UNITED STATES PATENT OFFICE.

METHOD ATTACHmG LEATHER SOLES TO SHOES Alexander 1). Macdonald, Maiden, Masa, assignor to Boston Blacking & Chemical (20., Boston, Mass., a corporation of Massachusetts No Drawing. Application November 30, 1934,

Serial .JNO. 755,369

4 Claims. (Cl. 12-142) Other objects of the invention will be apparent to those skilled in the. art to which this invention appertains from the accompanying disclosure and claims.

In the accomplishment of the above and other 15 objects, I have provided a method in which, in

its preferred form, there is-applied to the attaching surface of the leather sole a solution of rubber in an organic solvent wherein the rubber is in such condition that the resulting solution is of sufliciently low viscosity to penetrate readilyinto the sole leather and to secure a firm anchorage therein. To the attachin surface of the fabric shoe bottom is applied an adhesive composition preferably comprising aqueously-dispersed rubber and an aqueous emulsion of rubber dissolved in an organic solvent, preferably comprising toluene and trichlorethylene. An anti-oxidant for rubber, de-

sirably phenyl-beta-naphthylamine, may be dissolved in the rubber solvent. The compositions thus applied to the sole and shoe bottom are permitted to dry and later activated, preferably with a relatively dilute. solution of rubber in an organic solvent and containing an anti-oxidant.

This activating solution is permitted to remain on the parts for a brief interval, for example,

10 to 15 seconds, after which the shoe parts are brought into juxtaposition, and the assemblage placed under sole-attaching pressure for a short time, for example, about 1 minute.

In carrying out the invention the shoe bottom and sole are preferably first prepared mechanically for the application of adhesive thereto.

The overlasted margin of the fabric upper may be prepared by roughing the surface of the fabric with a small emery wheel. To prepare the sole,-

the attaching surface thereof may be roughed with a wire brush. While this mechanical preparation of the shoe bottom and sole is not necessary in all cases and may be varied, in

general I find that a more secure and satisfactory attachment of sole and shoe bottom is accomplished by a preliminary mechanical preparation such as hereinbelow outlined. a A leather penetrative solution of rubber in an organic solvent is applied'to the mechanically prepared attaching surface of the sole, and usually only to the marginal or peripheral portion thereof. This composition may contain sulphur (for vulcanization) and an anti-oxidant and v solved in an organic solvent. This adhesive compreferably the rubber is in such condition that it will readily penetrate into the leather to form a firm anchorage therein. This latter property may be produced, for example, by milling the rubber for a substantial length of time, such as 5 1 hour, whereby the rubber particles are reduced to small dimensions, but without producing depolymerization of the rubber. This adhesive composition is then permitted to dry in .which condition the deposited film issubstantially l0 transparent. An adhesive composition particularly advantageous for applying to the leather in accordance with this invention is as follows:

Yield: approximately 100 gallons.

The above composition may be prepared by heating the mixture of the sulphur and rosin together to a temperature of about 120 C. to 140 C. for about 1 to 2 hours, thereby producing 25 a material which will dissolve readily and completely in benzol. The sulphur-rosin material. and the smoked sheets are then dissolved in the benzol and the anti-oxidant, phenyl-beta-' naphthylamine, may be added to the resulting 30 solution. The rosin-sulphur material provides a convenient means for getting the sulphur into solution' Obviously, sulphur may be introduced into the composition in other forms.

To the mechanically prepared overlasted por- 35 tion of the shoe bottom is applied an adhesive composition comprising aqueously-dispersed rub-- her and an aqueous emulsion of rubber disposition is then permitted to dry, in which condition the film deposited from the composition is substantially transparent. A particularly advantageous adhesive composition for application to the overlasted portion of the bottom of a fabric 5 shoe is asfollows:

Latex (containing rubber by weight) 87.5 gals. Rubber (hot rolled smoked sheetsmilled 1 hour) 1.13 lbs. 5 Benzol l- 1.04 gals. Tri-chlor-ethylene 6.02 gals. Toluene 1.88 gals. Phenyl beta naphthylamine 3.17 lbs. Nekal. 1.51 lbs. 55 'Water 4.15. gals.

Ethylene diamine 2.73 gals. Yield: approximately gallons.

The above composition may be prepared by w dissolving the smoked sheets and the phenyl-- beta-naphthylamine in a mixture of benzol, trichlor-ethylene and toluene and emulsifying the resulting solution in water containing dissolved Nekal. This aqueous emulsion and the ethylene diamine may then be added to the latex.

In the above composition the latex serves as a source of rubber, the adhesive material of the composition. The phenyl-beta-naphthylamine is an anti-oxidant and increases the aging properties of the rubber. The benzol, toluene and tri-chlor-ethylene are rubber solvents and also solvents for the antioxidant. Toluene is radily emulsified and aids in the emulsification of other solvents associated therewith. The trichlor-ethylene associates readily with the rubber particles and assists in associating the dissolved anti-oxidant with the rubber. The smoked sheets serve to impart body" to the emulsion of the above solvents. The Nekal is an emulsifying agent which assists in dispersing the rubber solvents in water. Ethylene diamineis a rubber solvent and accelerator of vulcanization.

After the adhesive compositions which have been applied to the leather sole and to the shoe bottom have become dry, an activating composition is applied to the' dry surfaces of the adhesive compositions and permitted to stand for a. short period of time, such as from 10 to 15 seconds, whereupon the sole and shoe upper are broughtinto juxtapositionand the assemblage placed under a relatively high sole-attaching pressure, for example 80 pounds per square inch, for a short period of time, such as about 1 minute.

An activating solution suitable fonthe purposes of this invention is as follows:

Yield: approximately 100 gallons.

In the above composition the hot rolled crepe rubber provides rubber in small particle size which when dissolved forms a solution of low viscosity. The crepe rubber associated therewith imparts strength to the rubber deposited from the solution. The benzol is the rubber solvent, and the phenyl-beta-naphthylamine is the antioxidant.

The use of an activating composition such as described above renders more certain the adhesion of the shoe parts over the entire areas to be cemented, thus substantially eliminating socalled dry joints and providing an adhesive union ofleather sole to fabric upper of great strength and uniformity.

Testshave shown that an adhesive union produced between sole and shoe bottom in accordance with this invention has considerably greater strength and durability than has been attained by the use of ordinary rubber or latex cements.

Furthermore, by means of this invention, an adhesive union of leather sole to fabric upper particularly suited to resist deterioration under actual wearing conditions is provided.

Having described my invention, what I claim 5 as new and desire to secure by Letters Patent of the United States is:

1. The method of attaching leather soles to shoe bottoms which comprises applying to the attaching surface of, the leather sole a solution of 10 low viscosity rubber in an organic solvent, applying a rubber composition to the overlasted portion of the shoe bottom, permitting the applied compositions to dry, activating the deposited material with a rubber solvent, bringing the 15 leather sole and the shoe bottom into juxtaposition, and placing the assemblage under pressure.

2. The method of attaching leather soles to fabric shoe bottoms which comprises applying to 20 the attaching surface of the leather sole a solution of un-depolymerized, small particle size rubber in an organic solvent, applying to the overlasted portion of the shoe bottom an aqueous dispersion containing in the dispersed phase 25 rubber and an organic solvent for rubber, permitting the applied compositions to dry to transparent films, activating said films with a solution of rubber in an organic solvent, bringing the leather sole and the shoe bottom into juxtaposi- 30 tion, and placing the assemblage under pressure.

3. The method of attaching leather soles to fabric shoe bottoms which comprises applying to the attaching surface of the leather sole a solu-' tion of un-depolymerized, small particle size rub- 35 her in an organic solvent, applying to the overlasted portion of the shoe bottom an aqueous dispersion containing in the dispersed phase rubzer, phenyl-beta-naphthylamine, and at least one of the rubber solvents toluene and tri-chlor- 40 ethylene, permitting the appliedcompositions to dry to substantially transparent films, activating said films with a solution of rubber in an organic solvent, bringing the leather sole and the shoe bottom into juxtaposition, and placing 45 the assemblage under pressure.

4. The method of attaching leather soles to fabric shoe bottoms which comprises applying t(. the attaching surface of the leather sole 8. solution of un-depolymerized, small particle size rub- 0 her in an organic solvent, applying to the overlasted portion of the shoe bottom rubber latex containing an aqueous emulsion of toluene and tri-chlor-ethylene, permitting the applied compositions to dry to substantially transparent films. activating said films with a dilute solution of rubber in an organic solvent, bringing the leath- ALEXANDER D. MACDONALD. 

